1. Field of the Invention
The present invention relates to a positioning device for positioning and stopping slide fastener stringers in an apparatus for finishing slide fasteners.
2. Description of the Prior Art
One typical positioning device incorporated in a slide fastener finishing apparatus is disclosed in Japanese Patent Publication No. 49-44243 published on Nov. 27, 1984. The disclosed positioning device is generally shown in FIG. 10 of the accompanying drawings and comprises a pair of stopper arms A, A disposed below a pair of elongate slide fastener stringers B, B, respectively, fed by a pair of grippers C, C movable along a feed path for a predetermined interval. Each of the slide fastener stringers includes a plurality of rows of coupling elements mounted on and along one longitudinal edge of a stringer tape at longitudinal intervals. The positioning stopper arms A, A have bifurcated upper ends and are vertically movable to receive the longitudinal tape edges in their bifurcated upper ends for engaging the leading coupling element, thereby detecting slide fastener stringers B, B having travelled over the predetermined interval. In response to this detection, the grippers C, C are stopped and the slide fastener stringers B, B are cut by a pair of cutters G, G across element-free portions into individual fastener lengths which are then fed along to a discharge position. The slide fastener finishing apparatus also includes an end stop attachment unit D for attaching end stops to the slide fastener stringers B, B, a slider applicator E for mounting sliders F successively to the slide fastener stringers B, B, and a pair of grippers H, H movable along the feed path for feeding the slide fastener stringers B, B through the finishing apparatus.
Since the positioning stopper arms A, A move respectively in the same plane as the slide fastener stringers so as to receive the longitudinal tape edges in the bifurcated upper ends, the bifurcated upper ends are likely to miscatch the longitudinal tape edges when the stringer tapes are laterally undulated or locally swelled during advancing movement thereof. Such miscatched stringer portions could not be properly processed in the following processing stations and hence would result in unuseable slide fasteners.